This invention relates to a circuit arrangement for demodulating a frequency-differential, phase-modulated signal which consists of a plurality of modulated carriers. At the receiving end the signal is conducted to a plurality of correlators whose d.c. voltages assume values indicative of the phase states of the carriers. With the d.c. voltages emitted from the correlators, binary words indicating the phase states are obtained, and these binary words are stored successively in binary stores. The transmitted data are then obtained from the differences between these words.
In frequency-differential phase modulation, the data which are to be transmitted are transmitted with the aid of the phase difference of two carriers which have adjacent frequencies. When the data is restored from the modulated signal, the phase states of the carriers are measured by means of correlators. If the transmitted signal consists of n carriers, in known circuit arrangements, 2n correlators, n phase modulators and n-1 analogdigital converters are provided for analyzing the phase states of the modulated carriers. If, for example the number n = 16, a relatively large expenditure for circuitry is required for the 16 phase modulators and 15 anolog-digital converters.
An object of the invention, therefore, is to provide a demodulator for the demodulation of a frequency-differential, phase-modulated signal which overcomes the foregoing disadvantages and which is characterized by a relatively low cost construction.